Enumerable.Distinct Enumerable.Distinct Enumerable.Distinct Enumerable.Distinct Method

Definição

Retorna elementos diferentes de uma sequência.Returns distinct elements from a sequence.

Sobrecargas

Distinct<TSource>(IEnumerable<TSource>) Distinct<TSource>(IEnumerable<TSource>) Distinct<TSource>(IEnumerable<TSource>) Distinct<TSource>(IEnumerable<TSource>)

Retorna os elementos distintos de uma sequência usando o comparador de igualdade padrão para comparar valores.Returns distinct elements from a sequence by using the default equality comparer to compare values.

Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>) Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>) Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>) Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>)

Retorna os elementos distintos de uma sequência usando um IEqualityComparer<T> especificado para comparar valores.Returns distinct elements from a sequence by using a specified IEqualityComparer<T> to compare values.

Comentários

A sequência de resultados não é ordenada.The result sequence is unordered.

Distinct<TSource>(IEnumerable<TSource>) Distinct<TSource>(IEnumerable<TSource>) Distinct<TSource>(IEnumerable<TSource>) Distinct<TSource>(IEnumerable<TSource>)

Retorna os elementos distintos de uma sequência usando o comparador de igualdade padrão para comparar valores.Returns distinct elements from a sequence by using the default equality comparer to compare values.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TSource> ^ Distinct(System::Collections::Generic::IEnumerable<TSource> ^ source);
public static System.Collections.Generic.IEnumerable<TSource> Distinct<TSource> (this System.Collections.Generic.IEnumerable<TSource> source);
static member Distinct : seq<'Source> -> seq<'Source>
<Extension()>
Public Function Distinct(Of TSource) (source As IEnumerable(Of TSource)) As IEnumerable(Of TSource)

Parâmetros de tipo

TSource

O tipo dos elementos de source.The type of the elements of source.

Parâmetros

source
IEnumerable<TSource>

A sequência da qual os elementos duplicados serão removidos.The sequence to remove duplicate elements from.

Retornos

IEnumerable<TSource>

Um IEnumerable<T> que contém elementos distintos da sequência de origem.An IEnumerable<T> that contains distinct elements from the source sequence.

Exceções

Exemplos

O exemplo de código a seguir demonstra como Distinct<TSource>(IEnumerable<TSource>) usar o para retornar elementos distintos de uma sequência de inteiros.The following code example demonstrates how to use Distinct<TSource>(IEnumerable<TSource>) to return distinct elements from a sequence of integers.

List<int> ages = new List<int> { 21, 46, 46, 55, 17, 21, 55, 55 };

IEnumerable<int> distinctAges = ages.Distinct();

Console.WriteLine("Distinct ages:");

foreach (int age in distinctAges)
{
    Console.WriteLine(age);
}

/*
 This code produces the following output:

 Distinct ages:
 21
 46
 55
 17
*/
' Create a list of integers.
Dim ages As New List(Of Integer)(New Integer() _
                             {21, 46, 46, 55, 17, 21, 55, 55})

' Select the unique numbers in the List.
Dim distinctAges As IEnumerable(Of Integer) = ages.Distinct()

Dim output As New System.Text.StringBuilder("Distinct ages:" & vbCrLf)
For Each age As Integer In distinctAges
    output.AppendLine(age)
Next

' Display the output.
MsgBox(output.ToString)

' This code produces the following output:
'
' Distinct ages:
' 21
' 46
' 55
' 17

Se você quiser retornar elementos distintos de sequências de objetos de alguns tipos de dados personalizados, precisará implementar IEquatable<T> a interface genérica na classe.If you want to return distinct elements from sequences of objects of some custom data type, you have to implement the IEquatable<T> generic interface in the class. O exemplo de código a seguir mostra como implementar essa interface em um tipo de dados personalizado GetHashCode e Equals fornecer métodos e.The following code example shows how to implement this interface in a custom data type and provide GetHashCode and Equals methods.

public class Product : IEquatable<Product>
{
    public string Name { get; set; }
    public int Code { get; set; }

    public bool Equals(Product other)
    {

        //Check whether the compared object is null. 
        if (Object.ReferenceEquals(other, null)) return false;

        //Check whether the compared object references the same data. 
        if (Object.ReferenceEquals(this, other)) return true;

        //Check whether the products' properties are equal. 
        return Code.Equals(other.Code) && Name.Equals(other.Name);
    }

    // If Equals() returns true for a pair of objects  
    // then GetHashCode() must return the same value for these objects. 

    public override int GetHashCode()
    {

        //Get hash code for the Name field if it is not null. 
        int hashProductName = Name == null ? 0 : Name.GetHashCode();

        //Get hash code for the Code field. 
        int hashProductCode = Code.GetHashCode();

        //Calculate the hash code for the product. 
        return hashProductName ^ hashProductCode;
    }
}
Public Class Product
    Implements IEquatable(Of Product)

    Public Property Name As String
    Public Property Code As Integer

    Public Function Equals1(
        ByVal other As Product
        ) As Boolean Implements IEquatable(Of Product).Equals

        ' Check whether the compared object is null.
        If other Is Nothing Then Return False

        ' Check whether the compared object references the same data.
        If Me Is Other Then Return True

        ' Check whether the products' properties are equal.
        Return Code.Equals(other.Code) AndAlso Name.Equals(other.Name)
    End Function

    Public Overrides Function GetHashCode() As Integer

        ' Get hash code for the Name field if it is not null.
        Dim hashProductName = If(Name Is Nothing, 0, Name.GetHashCode())

        ' Get hash code for the Code field.
        Dim hashProductCode = Code.GetHashCode()

        ' Calculate the hash code for the product.
        Return hashProductName Xor hashProductCode
    End Function
End Class

Depois de implementar essa interface, você pode usar uma sequência de Product objetos Distinct<TSource>(IEnumerable<TSource>) no método, conforme mostrado no exemplo a seguir:After you implement this interface, you can use a sequence of Product objects in the Distinct<TSource>(IEnumerable<TSource>) method, as shown in the following example:

Product[] products = { new Product { Name = "apple", Code = 9 }, 
                       new Product { Name = "orange", Code = 4 }, 
                       new Product { Name = "apple", Code = 9 }, 
                       new Product { Name = "lemon", Code = 12 } };

//Exclude duplicates.

IEnumerable<Product> noduplicates =
    products.Distinct();

foreach (var product in noduplicates)
    Console.WriteLine(product.Name + " " + product.Code);

/*
    This code produces the following output:
    apple 9 
    orange 4
    lemon 12
*/

Dim products() As Product = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "orange", .Code = 4}, 
     New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "lemon", .Code = 12}}

' Exclude duplicates.

Dim noduplicates = products.Distinct()

For Each product In noduplicates
    Console.WriteLine(product.Name & " " & product.Code)
Next

' This code produces the following output:
'
' apple 9
' orange 4
' lemon 12
' 

Comentários

Esse método é implementado usando a execução adiada.This method is implemented by using deferred execution. O valor de retorno imediato é um objeto que armazena todas as informações necessárias para executar a ação.The immediate return value is an object that stores all the information that is required to perform the action. A consulta representada por esse método não é executada até que o objeto GetEnumerator seja enumerado chamando seu método diretamente ou usando foreach no Visual C# ou For Each em Visual Basic.The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in Visual C# or For Each in Visual Basic.

O Distinct<TSource>(IEnumerable<TSource>) método retorna uma sequência não ordenada que não contém valores duplicados.The Distinct<TSource>(IEnumerable<TSource>) method returns an unordered sequence that contains no duplicate values. Ele usa o comparador de Defaultigualdade padrão,, para comparar valores.It uses the default equality comparer, Default, to compare values.

Em Visual Basic sintaxe de expressão de consulta Distinct , uma cláusula se traduz em uma invocação Distinctde.In Visual Basic query expression syntax, a Distinct clause translates to an invocation of Distinct.

O comparador de Defaultigualdade padrão,, é usado para comparar valores dos tipos que IEquatable<T> implementam a interface genérica.The default equality comparer, Default, is used to compare values of the types that implement the IEquatable<T> generic interface. Para comparar um tipo de dados personalizado, você precisa implementar essa interface e fornecer seus próprios GetHashCode métodos Equals e para o tipo.To compare a custom data type, you need to implement this interface and provide your own GetHashCode and Equals methods for the type.

Para obter um exemplo que IEqualityComparer<T> usa o para definir um comparador personalizado, consulte. Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>)For an example that uses IEqualityComparer<T> to define a custom comparer, see Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>).

Veja também

Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>) Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>) Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>) Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>)

Retorna os elementos distintos de uma sequência usando um IEqualityComparer<T> especificado para comparar valores.Returns distinct elements from a sequence by using a specified IEqualityComparer<T> to compare values.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TSource> ^ Distinct(System::Collections::Generic::IEnumerable<TSource> ^ source, System::Collections::Generic::IEqualityComparer<TSource> ^ comparer);
public static System.Collections.Generic.IEnumerable<TSource> Distinct<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, System.Collections.Generic.IEqualityComparer<TSource> comparer);
static member Distinct : seq<'Source> * System.Collections.Generic.IEqualityComparer<'Source> -> seq<'Source>
<Extension()>
Public Function Distinct(Of TSource) (source As IEnumerable(Of TSource), comparer As IEqualityComparer(Of TSource)) As IEnumerable(Of TSource)

Parâmetros de tipo

TSource

O tipo dos elementos de source.The type of the elements of source.

Parâmetros

source
IEnumerable<TSource>

A sequência da qual os elementos duplicados serão removidos.The sequence to remove duplicate elements from.

comparer
IEqualityComparer<TSource>

Um IEqualityComparer<T> para comparar valores.An IEqualityComparer<T> to compare values.

Retornos

IEnumerable<TSource>

Um IEnumerable<T> que contém elementos distintos da sequência de origem.An IEnumerable<T> that contains distinct elements from the source sequence.

Exceções

Exemplos

O exemplo a seguir mostra como implementar um comparador de igualdade que pode ser Distinct usado no método.The following example shows how to implement an equality comparer that can be used in the Distinct method.

public class Product
{
    public string Name { get; set; }
    public int Code { get; set; }
}

// Custom comparer for the Product class
class ProductComparer : IEqualityComparer<Product>
{
    // Products are equal if their names and product numbers are equal.
    public bool Equals(Product x, Product y)
    {
       
        //Check whether the compared objects reference the same data.
        if (Object.ReferenceEquals(x, y)) return true;

        //Check whether any of the compared objects is null.
        if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null))
            return false;

        //Check whether the products' properties are equal.
        return x.Code == y.Code && x.Name == y.Name;
    }

    // If Equals() returns true for a pair of objects 
    // then GetHashCode() must return the same value for these objects.

    public int GetHashCode(Product product)
    {
        //Check whether the object is null
        if (Object.ReferenceEquals(product, null)) return 0;

        //Get hash code for the Name field if it is not null.
        int hashProductName = product.Name == null ? 0 : product.Name.GetHashCode();

        //Get hash code for the Code field.
        int hashProductCode = product.Code.GetHashCode();

        //Calculate the hash code for the product.
        return hashProductName ^ hashProductCode;
    }

}
Public Class Product
    Public Property Name As String
    Public Property Code As Integer
End Class

' Custom comparer for the Product class
Public Class ProductComparer
    Implements IEqualityComparer(Of Product)

    Public Function Equals1(
        ByVal x As Product, 
        ByVal y As Product
        ) As Boolean Implements IEqualityComparer(Of Product).Equals

        ' Check whether the compared objects reference the same data.
        If x Is y Then Return True

        'Check whether any of the compared objects is null.
        If x Is Nothing OrElse y Is Nothing Then Return False

        ' Check whether the products' properties are equal.
        Return (x.Code = y.Code) AndAlso (x.Name = y.Name)
    End Function

    Public Function GetHashCode1(
        ByVal product As Product
        ) As Integer Implements IEqualityComparer(Of Product).GetHashCode

        ' Check whether the object is null.
        If product Is Nothing Then Return 0

        ' Get hash code for the Name field if it is not null.
        Dim hashProductName = 
            If(product.Name Is Nothing, 0, product.Name.GetHashCode())

        ' Get hash code for the Code field.
        Dim hashProductCode = product.Code.GetHashCode()

        ' Calculate the hash code for the product.
        Return hashProductName Xor hashProductCode
    End Function
End Class

Depois de implementar esse comparador, você pode usar uma Product sequência de objetos Distinct no método, conforme mostrado no exemplo a seguir:After you implement this comparer, you can use a sequence of Product objects in the Distinct method, as shown in the following example:

Product[] products = { new Product { Name = "apple", Code = 9 }, 
                       new Product { Name = "orange", Code = 4 }, 
                       new Product { Name = "apple", Code = 9 }, 
                       new Product { Name = "lemon", Code = 12 } };

//Exclude duplicates.

IEnumerable<Product> noduplicates =
    products.Distinct(new ProductComparer());

foreach (var product in noduplicates)
    Console.WriteLine(product.Name + " " + product.Code);

/*
    This code produces the following output:
    apple 9 
    orange 4
    lemon 12
*/

Dim products() As Product = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "orange", .Code = 4}, 
     New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "lemon", .Code = 12}}

' Exclude duplicates.

Dim noduplicates = products.Distinct(New ProductComparer())

For Each product In noduplicates
    Console.WriteLine(product.Name & " " & product.Code)
Next

' This code produces the following output:
'
' apple 9
' orange 4
' lemon 12
' 

Comentários

Esse método é implementado usando a execução adiada.This method is implemented by using deferred execution. O valor de retorno imediato é um objeto que armazena todas as informações necessárias para executar a ação.The immediate return value is an object that stores all the information that is required to perform the action. A consulta representada por esse método não é executada até que o objeto GetEnumerator seja enumerado chamando seu método diretamente ou usando foreach no Visual C# ou For Each em Visual Basic.The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in Visual C# or For Each in Visual Basic.

O Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>) método retorna uma sequência não ordenada que não contém valores duplicados.The Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>) method returns an unordered sequence that contains no duplicate values. Se comparer Defaultfor null, o comparador de igualdade padrão,, será usado para comparar valores.If comparer is null, the default equality comparer, Default, is used to compare values.

Aplica-se a